Speed Sensor problems of the 2000 Chevrolet Suburban

Brake failure at low speeds. Almost caused a few accidents (parking lots and coming up to a stop sign or red light. These incidents happened over several months. I had brakes, calipers and rotors put on to try and fix the problem. The problem started out once so often and around Aug. 2005 it happened everytime I drove my vehicle and took it to the dealer and had it repaired. Both front speed sensors were removed and cleaned sensor mounting surfaces. To me this is a safety problem. This is nothing I could prevent from happening. Defective material. I had an older Suburban before this one and never had this problem. It was still running at 190,000 miles.